<!DOCTYPE html>
<html>
    <head>
        <meta charset="utf-8">
        <title>javascript</title> 
    </head>
    <body>        
    </body>
    <script type="text/javascript">/*可以不写type="text/javascript"*/
        document.write("使用JavaScript脚本语言循环输出 hello world")
        for(var i=0;i<3;i++){
            document.write("<h1>hello world!")
        }
    </script>
</html>